You can either use dpans2texi.el and make your own Emacs info documents from the dpANS3R preprint of the ANSI specification, or use Bill Schelter's gcl-info+texi.tgz, containing the Texinfo documents and gzip-compressed info files, that are (were?) distributed together with GCL (GNU Common Lisp).

Both will produce the entire ANSI Common Lisp specification as Emacs info files, but without the collection of X3J13 Issues and related discussions from the Hyperspec, because they are not part of the ANSI specification.